The present invention relates to an image processing apparatus and method therefor and recording medium, and more particularly to an image processing apparatus and method therefor and recording medium suitable for processing monochrome multivalued images used in medical care.
Conventionally, when taking images of human body and the like using CT scanner, MR scanner (MRI), etc. and carrying out diagnosis in a medical field, for example, the images are usually displayed on a display such as a CRT, LCD or the like of the CT scanner, MR scanner, etc. to be observed. The display images are commonly monochrome gradation information, that is, gray scale images.
Hard copies of the images shown on the display can also be made by a printer such as an ink jet printer to be used for the diagnosis. To achieve this, analog image data are captured from a device like a CT scanner or MR scanner to be supplied to a display such as a CRT or LCD, and to be converted into digital image data and supplied to a printer like an ink jet printer. Alternatively, image data with digital gradation information are captured from a device such as a CT scanner or MR scanner to be supplied to a printer such as an ink jet printer. To make hard copies from digital image data with gradation information, that is, from multivalued image data by a printer like an ink jet printer, multivalued image data are converted into binary image data using various binarization techniques such as systematic dither, and the resultant binary image data are used to make hard copies.
The printer such as an ink jet printer, which makes hard copies from the binary image data obtained by converting the multivalued image data into binary image data, usually carries out binarization of the multivalued image data using a printer driver (software programs) to generate the binary image data, so as to obtain hard copy pictures with image quality comparable to the original images associated with the multivalued image data. The printer driver is usually attached to the printer.
Thus, although it must be considered that the image quality can be modified because of the loss of image information involved in converting the multivalued image into binary image, and hence the reduction in resolution is unavoidable, hard copy pictures are generally obtained of the image quality comparable to the original image with the multivalued image data.
However, in a specific application, the image quality of the hard copy pictures produced by the printer can differ considerably from the original image with the multivalued image data. For example, as for the hard copies made from monochrome multivalued image data captured from a device such as medical CT scanner or MR scanner, the image quality of the resultant hard copy pictures can sometimes differ considerably from the original images, the images on a display of the device such as a CT scanner or MR scanner. One of the reasons for this, is the loss of image information involved in converting multivalued images into binary images. Accordingly, the printers using a general purpose printer driver cannot achieve the required image quality of the hard copies. Apart from this, ink jet printers, for example, present another problem of producing hard copy pictures of different image quality from the same multivalued image data. This is due to the differences in the device types, ink types, ink discharge volumes from ink discharge orifices, spacing between ink discharge orifices in recording heads, and recording media.
Therefore, to achieve desired image quality of hard copy pictures in a specific application by the foregoing printers, it is unavoidable to iterate cut-and-try processings of making hard copies after carrying out suitable image processing of the multivalued image data until hard copy pictures with required image quality are obtained.
On the other hand, to reduce the load of repeating the cut-and-try processings, the following image processing has been studied. The processing converts, before making hard copies from the binary image data obtained by converting multivalued image data, the binary image data into multivalued image data to be displayed on the display, and applies suitable image processing on the multivalued image data with watching the images displayed on the monitor. For example, the assignee of the present application has filed several applications such as Japanese patent application laid-open Nos. 9-292869, 10-340339 and 11-126247.
These proposals, however, cannot accomplish satisfactory results as a whole, although they have made partial improvements.
Therefore, an object of the present invention is to provide, by solving the foregoing problems, an image processing apparatus and method therefor and recording medium capable of easily making hard copy pictures with image quality close to the image quality of an original image.
Another object of the present invention is to provide an image processing apparatus and method therefor and recording medium capable of generating hard copy pictures of an original image with improved image quality meeting a desired quality.
Still another object of the present invention is to provide an image processing apparatus and method therefor and recording medium capable of monitoring images with image quality close to their hard copy pictures before actually making hard copy pictures of the original image.
Finally, another object of the present invention is to provide a print result assurance method, apparatus and recording medium, which can ensure the print results of the image processing.
According to a first aspect of the present invention, there is provided an image processing apparatus comprising: a histogram generator for generating a histogram by dividing pixels constituting multivalued image data into levels; a multivalued image processor for changing levels of at least part of the pixels of the multivalued image data using the histogram generated by the histogram generator; and binarization means for converting the multivalued image data, the levels of at least part of the pixels of which are changed by the multivalued image processor, into binary image data representing pseudo-gray levels.
According to a second aspect of the present invention, there is provided an image processing method comprising: a histogram generating step of generating a histogram by dividing pixels constituting multivalued image data into levels; a multivalued image processing step of changing levels of at least part of the pixels of the multivalued image data using the histogram generated by the histogram generator; and a binarization step of converting the multivalued image data, the levels of at least part of the pixels of which are changed by the multivalued image processor, into binary image data representing pseudo-gray levels.
According to a third aspect of the present invention, there is provided a recording medium having computer readable image processing program code means for causing computer to process image data, the image processing program code means causing the computer to execute: a histogram generating step of generating a histogram by dividing pixels constituting multivalued image data into levels; a multivalued image processing step of changing levels of at least part of the pixels of the multivalued image data using the histogram generated by the histogram generator; and a binarization step of converting the multivalued image data, the levels of at least part of the pixels of which are changed by the multivalued image processor, into binary image data representing pseudo-gray levels.
According to a fourth aspect of the present invention, there is provided a print result assurance method of ensuring print results of image processing by an image processing apparatus, the print result assurance method comprising the step of: inputting into the image processing apparatus a password that is set in and proper to a specific recording medium; and enables the image processing apparatus to print when the password is correct.
According to a fifth aspect of the present invention, there is provided an apparatus for ensuring print results of image processing, the apparatus comprising: means for inputting password that is set in and proper to a specific recording medium; and means for allowing printing when the password is correct.